Green energy producer Canadian Hydro Developers Inc. (TSX:KHD) bought itself some time Tuesday to nail down a better takeover offer than TransAlta Corp.’s (TSX:TA) hostile bid. An Alberta Securities Commission panel unanimously turned down TransAlta’s request to block Canadian Hydro’s shareholder rights plan, or “poison pill,” which will now remain in effect until Sept. 21. “The ASC ruling is the best possible outcome for our shareholders,” Canadian Hydro chairman Dennis Erker said in a statement.

Canadian Hydro enacted its shareholder rights plan in April of last year, before TransAlta publicly expressed interest, as a means to protect its investors in the event of an unsolicited takeover bid. The poison pill makes it difficult and costly for a would-be acquirer to pursue its target for the plan’s 60-day duration.

“This upholds our ability to pursue opportunities in order to find the bet strategic alternative for the company,” Erker said.

As part of its argument to the ASC to dismiss TransAlta’s request, Canadian Hydro said it was “engaged with extensive discussions” with many potential white knight bidders, including a “leading international financial institution based in New York.” TransAlta, a Calgary-based utility with extensive power generation assets, has not yet decided on whether to extend or sweeten its bid, worth $654 million.

“We’re aware of the Alberta Securities Commission’s decision, but currently our offer is still open until 6 p.m. Calgary time this Thursday and we have not yet reached a decision if we will extend our offer past the expiry time,” said Michael Lawrence, a spokesman for the Calgary-based power producer. Lawrence did not comment on how TransAlta would react should a competing bidder emerge. “We believe that we’ve presented them with a very compelling and attractive offer. We’ll have to wait and see who comes forward,” he said.